1. Field of the Invention
The present invention relates to a golf club such as an iron, wood or putter, and more particularly, to an improvement in the structure for joining the head and hosel part of the golf club.
2. Prior Art
Conventionally, as shown in FIGS. 4 and 5, the head portion of, for example, an iron club is obtained from a head a made of steel (Be--Cu), stainless steel (SuS) or aluminum bronze, etc. and a hosel part (merely called "hosel") b by forging or casting them into an integral unit. The thus obtained head portion is connected to a shaft d by inserting and fastening one end of the shaft d in place into a shaft insertion hole c of the hosel b. A ferrule e, which is plastic, etc., is mounted at the upper end of the hosel b where the shaft d is inserted.
In a golf club having the structure as described above, the head a and hosel b are formed as an integral unit from the same material. Accordingly, if, for example, the head a is made of an iron material, the weight of the hosel b, which is also of an iron material, becomes as heavy as approximately 40 g, thus increasing the overall weight of the head portion. Furthermore, since the head a and hosel b are a single unit, the hosel b is not replaceable. In addition, as seen from FIG. 5, the position of the center of gravity G (or the sweet spot) of the head a is offset toward the upper portion of the head face on the heel side of the head a. Thus, the head a tends to have a high center of gravity.
Furthermore, since the hosel b consists of the same high-rigidity material used for the head a, the ferrule e made of a low-rigidity material such as plastic, etc., must be mounted in the position where stress is concentrated in the shaft d in order to prevent breakage of the shaft d, and this design causes the cost of the golf club to increase.